(I wasn't sure what subforum to put this under.)
So. There has always been "that guy". The one that is always a jerk, no matter what in and out of school issues he has.
Well, I have encountered "that guy". I need help.
The annoyance comes in the form of a boy named, let's say, B. Now, I know B has some issues. He has "momma trauma" where he isn't in the greatest terms with his mother, and it doesn't help everyone always makes fun of him because he is Jewish. (I do not, yet he seems to hate me most?) By being a jerk to everyone, B is only bringing attention to his own issues, which leads him to being made fun of.

Now, I always try to tolerate everyone. We got along ok, and became friends. At some point or another, he had a sudden change of heart, for no reason at all. I became the target of his torment. He seemed to have the most "fun" when messing with me. It was a nuisance, sure, but this recent incident has me worried, angry, and somewhat scared.

Today, all of our friends are at lunch. We eat together, though B sits with us. My friends are M, K, and J. I got up to buy a snack, and when I got back, my lunchbox was gone. I questioned my friends who "knew nothing". Eventually, B got up to "get a binder from his locker". At this point, it was already painstakingly clear he had it. I felt like chasing him, but I knew it would be to no avail. He came back, and the rest of lunch pretty much passed with me trying to find any shred of evidence as to where he put it.

Lunch ends. He tells me this; "I wanted to break into your locker and plant it there, but the school cameras would have caught me. I put it into G's (another friend) locker instead." We go to get it, and I swear he puts in the wrong combination 4-5 times before we're almost late to math. After math, he said, he would get it back.

Fast forward to after my math class. The day is over. I'm waiting by G's locker, when G arrives a few minutes later. Obviously annoyed at this point, I watch as he opens the locker. It isn't in there. I'm in a frenzy now. I'm going ballistic when he starts laughing so hard he was going to pop (the fatty!), and points at R (Obviously not so friendly with him at this point), who's holding a camera. He filmed the whole thing on B's phone, who wants to humiliate me. On top of that, I'm cursing religiously during the video. (I've kind of had enough with him.)

So now I'm in a predicament. Every time I offer friendship to him, he spits it at my feet, all while using the whole dictionary of derogatory terms and thieving. I need advice. And has anyone else been through a horrible situation with a bully?

I'm pretty sure I'll get chastised for going here by someone with advice such as "ignore him and he'll stop". (You can try that if you want to - I did and it only made things worse 25+ years ago)

Here it is - go Old Testament on this dude. Eye for an eye, tooth for a tooth. Fight fire with fire.
An old friend of mine once said "2 wrongs don't make a right, but it makes an even."

So dude likes to sneak around and be sneaky in order to humiliate. Two can play that game.

btw - If there is somebody out there that wants to tell me I'm wrong, their post had better start out "thephantombrain: I was mercilessly bullied and you are wrong...."

Mysterious:  Your profile says you're 23, but you obviously aren't.  How old are you?  My answer would quite honestly depend on your age. I'm guessing you are a high schooler or middle schooler, but what age and grade?

If the person is repeatedly doing something such as this, I would suggest trying to do anything, except become friends. Friendship is only good if both sides like each other, and if one of them acts in a way such as this, don't befriend them. Since he seems to be rejecting your offerings of friendship, that already means that you should not try to befriend them. There are a few options, none of them good. There's the first option: totally avoid the person. Good luck with that, sometimes it can make things worse, but if you can manage to completely avoid them, or ignore them, do so. Unnecessary conflict is unnecessary. Option two: talk it out. I believe you might have mentioned trying to do that, and it coming to no avail, so maybe not.  Option three: tell a teacher/guidance counselor. I know that this is an overused saying, and it's pretty much a 50/50 shot, but it might be worth taking the chance. Option four: retaliate. Do whatever you can to bring him down a peg. React. Destroy him from the inside, and you will win. Option five: fight. Challenge him to a brawl. Winner takes all. Again, not many of the options are pretty, but you can take anyone of those paths. I would try personally go through them in order, or maybe in reverse order. Depends on your specific situation. I have nothing past that. Good luck.

It's simple. Just report him as a bully. Schools have really been cracking down on bullies lately, and just the word "bully" can get someone suspended. I strongly suggest you report him to an authority figure that you trust. I think that would clear things up pretty quickly. And if he gets aggressive, go to the police.